Lipstick is one of the most widely used cosmetics. Formulating a new commercially practicable lipstick composition can be a difficult task because the composition must satisfy a number of criteria. In particular, a commercial lipstick composition should have most (if not all) of the following characteristics:
(a) it should be free from discoloration, specks of grit, pinholes and other imperfections;
(b) it should have a desirable consistency;
(c) it should not be too dry or brittle and at the same time oil droplets should not form on its surface;
(d) the composition should have a high enough melting point to assure that it does not melt under hot storage conditions (e.g., in a purse left in the sun) and that it is sufficiently hard and strong to enable it to be molded into stick form and to withstand normal use without breaking;
(e) it should be soft enough so that it can be easily applied to the lips;
(f) it should have a pleasant taste and odor or it should be tasteless and odorless; and
(g) it should have desirable film forming properties, e.g., films formed from the composition should be free from tackiness and have an emollient feel without imparting a sensation of dryness, and the resulting film should be durable.
In addition to the foregoing characteristics, an important criterion is that there should be little or no tendency for the coloring materials in the lipstick to migrate to the edges of the lips and onto the surrounding skin. Such migration, when it occurs, is known as "feathering."